// const querystring = require("querystring");
// let url = "a=1&b=2";
// console.log(querystring.parse(url))
// let obj = {a:1,b:2};
// console.log(querystring.stringify(obj))


// const a = 0;
// const b = a ?? 100;
// console.log(b);// 100
const userName = localStorage.getItem("userName") ?? "zhangsan"